Question

我只想一次更新计数表，但是它会不断循环更新，有人可以帮助我。

ionic

Answer 1

也许，您可以做这样的事情，虽然不是什么都完美，但是它给您一个很好的主意。

oldCount->您可以从document.getData（）读取它

 var docRef = db.collection(REFERRAL_CODE_KEY).doc(referral_code);    
 docRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
 @Override
 public void onComplete(@NonNull Task<DocumentSnapshot> task) {
    if (task.isSuccessful()) {
        DocumentSnapshot document = task.getResult();
        if (document.exists()) {
            Log.d(TAG, "DocumentSnapshot data: " + document.getData());
            //read oldCount here from document.getData()
             Map<String, Object> docData= new HashMap<>();
             docData.put(REFERRAL_COUNT, oldcount + 1);
             docRef.set(docData)
             .addOnSuccessListener(new OnSuccessListener<Void>() {
                 @Override
                public void onSuccess(Void aVoid) {
                   Log.d(TAG, "DocumentSnapshot successfully written!");
                 }
             })
            .addOnFailureListener(new OnFailureListener() {
                 @Override
                 public void onFailure(@NonNull Exception e) {
                     Log.w(TAG, "Error writing document", e);
                 }
            });
        } else {
            Log.d(TAG, "No such document");
        }
    } else {
        Log.d(TAG, "get failed with ", task.getException());
    }
  }
});

Answer 2

您可以分离侦听器，以使回调不再被调用。根据官方文件https://firebase.google.com/docs/firestore/query-data/listen#detach_a_listener，您需要使用remove方法来分离侦听器

Query query = db.collection("cities");
ListenerRegistration registration = query.addSnapshotListener(
        new EventListener<QuerySnapshot>() {
            // ...
        });

// ...

// Stop listening to changes
registration.remove();

Firestore无限循环更新

2 个答案: